Reinforcing-bar for concrete construction.



P. T. LARGE.

REINFO G BAR FOR oouonmn CONSTRUCTION.

LIGATION FILED APR. 5. 1907.

93 1 ,320. Patented Aug. 17, 1909.

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NORTH TONAWANDA, NEW YORK, ASSIGNOR TO BUFFALO STEEL COMPANY, OFTONAWANDA, NEW YORK.

REINFORCING-ZBAR FOR CGNCRETE CONSTRUCTION.

Specification of Letters Patent.

' Patentedhug. 17, 1909.-

Application filed April 5; 1907. Serial No. 366,515.

- and State of New York, have invented a new and'nseful Improvement inReinforcing- Bars for Concrete Construction, of whichthe following is aspecification.

This invent-ion relates to improvement-s in reinforcing bars forconcrete construe tion,'and more particularly to that class of barswhich are commonly known as twisted bars.

Twisted bars of square crosssection have long been used, The corners ofthese bars form sharp helical edges which wind' about the bar while thesides or surfaces of the bar between the corners remain fiat. It hasbeen found that these sharp or wedge-like helical edges and theintervening flat surfaces do not form a firm and continuous union withthe concrete when embedded therein for the reason that the concretetends to shrink away from the flat surfaces and. the sharp corners voredges of the bar tend to cleave the concrete, causing it to crack.

"he object of this invention is toovercome these objectionsbyconstructing a twisted reinforcing bar provided with helical ribs orridges having broad or rounded peaks instead of sharp or wedge-likeedges, and in. which there are no flat sides or surfaces between theridges. Such a bar, when en'ibedd'ed in the concrete, forms ainoreintiinate and continuous union therewith and does not tendlto cleave theconcrete nor perinit any movementthereof independent of the bar.Moreover, in twisting square bars, the corners of the bar which. formthe helical.

ridges, being a greater distance from the length of the bar as isdesirable for the best results." Around bar, on the other hand, owing tothe uniform distance of all parts of the surface metal from its center,can be twisted to a much greater degree without rupturing such surfacemetal. It is, therefore, a further object of this invention to employ inthe place of the twisted square bars heretofore used, a twisted roundbar provided with suitable helical ribs or ridges. Inasmuch as thetwisting of such a round bar does nottend to diminish its strengthand-as it has no sharp edges or corners to be ruptured thereby, the barcan be twisted to the extent necessary to give the desired angle orpitch to the helical ridges.

lnthe accompanying drawings: Figure 1 represents a perspective view of asection of' a reinforcing-bar embodying the invention. Fig. 2 is across-section of the same. Fig. 3 is a perspective view of the barbefore the same is twisted. Fig. 4 is a cross-section of atwisted barofslightly modified form.

Like letters of reference refer to like parts in the several figures.

A represents a reinforcing bar which is round in cr0ss-sect-ion,-as willappearfrom Fig. 2, and is provided at suitable intervals upon itssurface'with helicalribs or ridges a a separated by convex portions a aof such surface. The ribs or ridges, shown in Figs. 13, aresubstantially semicircular in cross-section, which is preferable, butthey could also be of somewhat different cross sectional shape, forinstance, as shown in Fig. 41-, in which the edges are of substantiallyrectangular cross-section. The ridges .in both bars have broad and'nioreor less flat peaks ascontradistinguished from 1' rp or wedge-like peaks.In the drawing our of these ribs or ridges are shown, but it is obviousthat a greater or less number could be used, dependingupon the size ofthe-bar and the nature of the work for which it is intended. In makingthese bars, the bar with the straight longitudinal ribs or ridges, shownin Fig. 3, is produced by rolling be- ;t-wecn suitable rolls forming'apass of a shape corresponding to the cross-sectional shape of the bar.This bar is then twisted, preferably while hot, in a. well known mainner. By thus rolling the bar in a substantially circular pass itacepii-rcs the additional strength and elasticity of a round bar, and byforming the ribs therein in the same operation the bar with its ribs canbe produced cheaply as the common square bar.

The sides or surfaces 0. a ofthe bar be tween the ribs instead of beingflat, as in twisted square bars, are convexed. As the concrete will themore firmly adhere to such convexed surfaces, a close union between theits'len th; the said bar being otherwise free bar and the concrete isthus obtained. of surface irregularities, every eripheral I claim as myinvention i portion of the bar being substantia 1y convex.

A reinforcing bar for concrete which com- Witness my hand, this 29th dayof March, 5 prises a round bar having a plurality of 1907/ ylongitudinal ribs of uniform cross-section PRESTON T LARGE spaced aboutthe bar, said bar being subsequently twisted, whereby said ribs are made,Witnesses:

to extend'continuously and in the same di- J. G. Josnrii, 10 i'ection,helically of the bar and throughout FRED R. LARGE.

